The parents have an empty nest. Literally.

“Our” 2012 bald eagle kids are grown up and mostly gone, though some are hanging around the nest, as is their wont.

There were three known, active bald eagle nests in the northern Mount Vernon area this spring where adults raised young. In the last week, observers who monitor the nests say that this year’s young appear to have fledged.

For the past several years, two bald eagle pairs have nested along the Potomac River in the Mount Vernon area. And for the first time, another pair built their nuptial lair at the seemingly inhospitable intersection of Route 1 and the Capital Beltway on the top of a metal utility tower.

Bald eagles that hatch in April in this area usually can fly and leave the nest in early June. 

The Bald Eagle

The bald eagle (Haliaeetus leucocephalus) is a large raptor weighing from 10 to 14 pounds with a wingspan of around 8 feet. It has been America’s symbol since 1782, having won out over Benjamin Franklin’s suggestion of the turkey.

Bald eagles are mostly brown until their fourth or fifth year, when they acquire a white head and tail. They usually choose the tops of large trees for their nests and typically return to the same site each year and enlarge the previous year’s nest.  Nests, made of sticks, moss and other materials, can reach 10 feet across and weigh a half ton. The eagles frequent aquatic habitats where they can find fish, their preferred food. 

The recovery of the bald eagle is a real American success story. The pre-Columbian bald eagle population in the lower 48 states was an estimated 100,000 birds. By 1963, there were only 417 known nesting pairs.

Scientists determined in the early 1970s that DDT, a commonly used pesticide, moved up the food chain and was thinning egg shells during incubation so young birds did not hatch. In 1967, the U.S. Fish and Wildlife Service listed the bald eagle as endangered.

In 1972, the Environmental Protection Agency banned DDT, a major step credited with restoring the population. In 2007, the fish and wildlife service removed the bald eagle from the endangered species list, announcing the recovery of this bird. The bald eagle is still protected under other laws.

Larry Cartwright, leader of the Friends of Dyke Marsh breeding bird survey, said, “Bald eagles are adapting to the presence of humans in the area. They, like ospreys, have made the transition. Unfortunately, many or most species can’t.”

The severe erosion of Dyke Marsh, documented in a 2010 U.S. Geological Survey study, is causing tree loss along the shoreline, making it more difficult for raptors to find suitable habitats, Cartwright said.     

Bryan Watts, director of William and Mary College’s Center for Conservation Biology, commented on the center’s 50 years of Virginia bald eagle surveys: “For Virginia, in terms of a comeback, the population has increased from a low of about 20 known pairs in the early 1970s to 730 pairs in 2011. That’s about a 35-fold increase.

"It’s an incredible success story. We never thought 20 years ago that we would see eagles nesting with people, but we have quite a few pairs now in residential neighborhoods and on golf courses. It’s quite an incredible turn of events.” 

Because of budget constraints, the conservation center did not monitor Potomac River nests this year.